將替換字符串替換爲鍵並將替換字符串替換爲值。蟒蛇

Question

我有一個字典字符串被替換爲爲keys及其替換作爲值。除了用標記來查看字符串標記外，還有更好/更快的替換方法嗎？

我已經做了這樣：

segmenter = {'foobar':'foo bar', 'withoutspace':'without space', 'barbar': 'bar bar'} 

sentence = "this is a foobar in a barbar withoutspace" 

for i in sentence.split(): 
    if i in segmenter: 
    sentence.replace(i, segmenter[i]) 

Answer 1

字符串在Python是不可改變的。所以，str.replace返回一個新的字符串，而不是修改原始字符串。您可以使用str.join()和列表理解這裏：

>>> segmenter = {'foobar':'foo bar', 'withoutspace':'without space', 'barbar': 'bar bar'} 
>>> sentence = "this is a foobar in a barbar withoutspace" 

>>> " ".join([ segmenter.get(word,word) for word in sentence.split()]) 
'this is a foo bar in a bar bar without space' 

與str.replace的另一個問題是，它也將與

"abar barb"更換的話就像"abarbarb"。

Answer 2

re.sub可以調用返回的替代

segmenter = {'foobar':'foo bar', 'withoutspace':'without space', 'barbar': 'bar bar'} 
sentence = "this is a foobar in a barbar withoutspace" 

import re 

def fn(match): 
    return segmenter[match.group()] 

print re.sub('|'.join(re.escape(k) for k in segmenter), fn, sentence)